phones down for maintenance in the middle of the business day AGAIN!

So our business phones suddenly stop working AGAIN (third time this month).   Incoming calls go to voice mail and outgoing calls get fast busy signal (after ringing the other end making it look like we called them and hung up on them). 

Comcast of course says this is a maintenance issue that they are already aware of and that it will probably be fixed in a couple of hours.  Well, in a couple of hours my business day will be nearly over.  What's the point of having a business phone if you can't use it during business hours? 

Why do other companies schedule maintenance in the middle of the night and give you 30 days notice of upcoming maintenance windows so that you can schedule things around it?   Why doesn't comcast business do this?

Checked into getting Vonage and see lots of posts to various boards that comcast actually causes vonage and skype traffic to degrade (to nearly the level of their own service?) and doesn't allow some types of SIP traffice at all, so those aren't really options either.